In many telecommunication systems, communications networks are used to exchange messages among several interacting spatially-separated devices. Networks may be classified according to geographic scope, which could be, for example, a metropolitan area, a local area, or a personal area. Such networks may be designated respectively as a wide area network (WAN), metropolitan area network (MAN), local area network (LAN), or personal area network (PAN). Networks also differ according to the switching/routing technique used to interconnect the various network nodes and devices (e.g., circuit switching vs. packet switching), the type of physical media employed for transmission (e.g., wired vs. wireless), and the set of communication protocols used (e.g., Internet protocol suite, SONET (Synchronous Optical Networking), Ethernet, etc.).
Wireless networks are preferable for mobile devices that have dynamic connectivity needs and/or ad hoc (e.g., rather than fixed topology) network architectures. Wireless networks employ intangible physical media in an unguided propagation mode using electromagnetic waves (e.g., radio, microwave, infra-red, optical, etc.). Thus, wireless networks may facilitate user mobility and rapid field deployment.
To satisfy increasing bandwidth demands for wireless communications systems, some communication schemes may allow multiple user terminals to communicate with a single access point using shared channel resources while maintaining high data throughput. Given limited communication resources, it may be desirable to reduce the amount of traffic passing between the access point and the multiple terminals.